The largest wastewater treatment plants can be defined in several ways.
The largest in term of capacity, both during dry and wet-weathers, is the Jean-R.-Marcotte Wastewater Treatment Plant in Montreal. With full secondary treatment of effluents it would be the Deer Island Waste Water Treatment Plant of Boston. In terms of area occupied it is by far Melbourne's Western Treatment Plant. Plant nameCity CountryOpening YearDry-weather capacity (m³ per day) Wet-weather capacity (m³ per day)Area (km2)NotesNew Delta Wastewater Treatment PlantEl Dabaa20237 500 0000.32Holds four Guinness World Records.Bahr El-Baqar Wastewater Treatment PlantPort Said20215 600 0000.65Jean-R.-Marcotte Wastewater Treatment PlantMontreal19842 780 0007 600 0000.67Secondary treatment planned for 2028.Detroit Wastewater Treatment PlantDetroit19402 460 0006 435 0000.53Wet-weather secondary treatment capacity limited to 3 520 000 m³/day.Passaic Valley Sewerage CommissionNewarkUSA19021 320 0002 700 000Full secondary treatment since 1982.Stickney Water Reclamation PlantChicago19302 665 0005 450 0001.67Blue Plains Advanced Wastewater Treatment PlantWashington D.C.19371 450 0004 073 0000.62Secondary treatment since 1959. Enhanced nutrient removal in 2014.Deer Island Waste Water Treatment PlantBoston19681 438 0004 542 0000.6Full secondary treatment since 1995.Abu Rawash Wastewater treatment plantGiza20211 600 0001.39Secondary treatment since 2021.Atotonilco de Tula PlantMexico City20152 000 0003 000 000Hyperion Water Reclamation PlantLos Angeles19251 041 0003 000 0000.81Wet-weather secondary treatment (since 1950) capacity limited to 1 821 000 m³/day.Kuryanovo wastewater treatment facilitiesMoscow19502 200 000Lyuberetskiye wastewater treatment facilitiesMoscow19633 000 000Seine Aval Wastewater Treatment PlantParis19401 460 0002 900 0008Shanghai Zhuyan I Wastewater Treatment PlantShanghai20041 700 000Stonecutters Island Sewage TreatmentHong Kong20012 765 000Bailonggang Wastewater Treatment PlantShanghai19992 000 000Gabal el Asfar Wastewater Treatment PlantCairo1 700 0002 500 0001.63Beckton Sewage Treatment WorksLondon18642 330 0001Morigasaki Water Reclamation CenterTokyo19661 540 0000.41Vienna wastewater treatment plantVienna2005680 0001 500 0000.39ETE BarueriBarueri19881 382 4000.86Beijing Huaifang Water PlantBeijing2017600 0000.16Built underground.Crossness Sewage Treatment WorksLondon1859564 0000.7Home to Sir Joseph Bazelgette beam engine house, victorian engineering.(beam engine trust), The engine was started by HRH The Prince of Wales, Albert Edward, who subsequently became King Edward VII. https://crossness.org.uk/Western Treatment PlantMelbourne1897485 000105Jebel Ali Wastewater Treatment PlantDubai2019375 0006.7Dasherkandi Sewage Treatment PlantDhaka2023350 000500 0000.26Largest sewage treatment plan in South Asia.McAlpine Creek Wastewater Treatment PlantCharlotte, N.C.1966290 950 Wastewater treatment capacities are expressed in cubic meters per day. 1000 cubic meters is 1 ML (mega liter). The area occupied by the plants are in square kilometers.
See also Water pollution Sewage treatment History of water supply and sanitation
References